[Comparison of the depth predictability of intra corneal ring segment implantation by mechanical versus femtosecond laser-assisted techniques using optical coherence tomography (OCT Visante(®))]. / Comparaison en tomographie en cohérence optique (OCT Visante(®)) de la prédictibilité de la profondeur d'implantation des anneaux intracornéens après tunnélisation mécanique versus tunnélisation assistée au laser femtoseconde.

UNLABELLED: Comparison of the depth predictability of intracorneal ring segment implantation by mechanical versus femtosecond laser-assisted techniques using optical coherence tomography (OCT Visante(®)). PURPOSE: To compare the depth predictability of intracorneal ring segment implantation by mechanical versus femtosecond laser-assisted techniques using OCT Visante(®). METHODS: This observational prospective study included, after patients' consent, 76 keratoconic eyes, of which 31 eyes (group 1) were operated using the mechanical technique and 45 eyes (group 2) with the femtosecond laser-assisted technique. The target depth was two-thirds of the peripheral corneal thickness, ranging from 5 to 7 mm in diameter. Every patient underwent high-resolution anterior segment OCT (OCT Visante(®)) measurement preoperatively and for the implant depth, 1 month postoperatively. Then two different sites were used to determine the segment depth, at the segment site and tangentially, at a distance of 700 µm central to the segment's inner edge. RESULTS: Both measurement techniques demonstrated that targeted implantation depth of 66% of the corneal thickness was not observed in either group. The mean difference between the preoperative expected depth and final segment implantation was 76.64 ± 48.76 µm in the manual technique and 85.85 ± 33.02 µm in the femtosecond-assisted technique, with no statistically significant difference between the groups. Comparison between the measurement sites showed implantation depth to be shallower, 54.93±6.03%, at the tangential site compared to 55.14 ± 8.08% at the implant site in group 1 and 56.17 ± 5.82% versus 58.88 ± 6.06%, respectively, in group 2. CONCLUSION: Both mechanical and femtosecond laser-assisted techniques showed a more superficial Intacs(®) placement than predicted. No statistically significant difference was observed in implantation depth between the two groups.

[Comparison of Lasik with femtosecond laser versus Lasik with mechanical microkeratome: predictability of flap depth, corneal biomechanical effects and optical aberrations]. / Comparaison entre le Lasik au laser femtoseconde et le Lasik au microkératome mécanique: prédictibilité des découpes, biomécanique cornéenne et aberrations optiques.

OBJECTIVES: To compare the predictability of flap thickness, high-order optic aberrations (HOAs), and biomechanical properties of cornea between patients treated by Lasik with mechanical microkeratome versus patients treated by FemtoLasik. SETTING: Department of ophthalmology, Pellegrin University Hospital, Bordeaux, France. PATIENTS AND METHODS: We conducted a retrospective study on 53 myopic patients who underwent Lasik with either mechanical microkeratome (MK group) or femtosecond laser (FS group). Refraction, central corneal thickness, high-order optic aberrations (HOAs), corneal hysteresis (CH), and corneal resistance factor (CRF), were analysed pre- and postoperatively in both groups. The central corneal thickness was measured with OCT-Visante(®) (Carl-Zeiss, Meditec), biomechanical parameters with ORA(®) (Reichert), and optical aberrations with the Wave Scan(®) (AMO) aberrometer. RESULTS: We included 44 eyes of 22 patients in the MK group and 62 eyes of 31 patients in the FS group. Preoperatively, the mean best-corrected visual acuity was 0.95 in both groups. In the MK group, the flap was significantly thicker than expected (162/130 µm), but in the FS group, there was no significant difference (117/120 µm). The biomechanical properties of the cornea were lower in both groups independently of the flap cutting technique. The HOAs increased after Lasik and were not influenced by the flap cutting technique. CONCLUSION: Neither mechanical microkeratome, nor femtosecond laser for flap creation, increases HOAs and the biomechanical changes of the cornea, according to ORA(®), significantly after Lasik.

[Intraorbital foreign body]. / Un corps étranger intra-orbitaire.

INTRODUCTION: Perforative intraorbital injuries can be potentially serious, and management depends on the type of projectile and its intraorbital trajectory. Medical imaging is an imperative part of the initial assessment. OBSERVATION: We report the case of a wooden intraorbital foreign body (arrow), with no functional or anatomical consequences, with a remarkable intraorbital trajectory analyzed by CT. DISCUSSION: The two main risks of these injuries are first mechanical, with possible bulb, nerve, muscle or bone complications, and second infectious. The CT scan or better yet MRI imaging provide a detailed analysis of the projectile's intraorbital trajectory in the orbital cavity. Infectious complications are promoted by the fat cells present in the orbit and must be systematically controlled with wide-spectrum antibiotics.

[Crystalline lens photodisruption using femtosecond laser: experimental study]. / Photodisruption cristallinienne par laser femtoseconde : étude expérimentale.

PURPOSE: The aim of this study was to analyze the interactions during femtosecond (fs) laser photodisruption in ex vivo porcine crystalline lenses and to study the parameters for laser interaction optimization. METHODS: An experimental femtosecond laser was used. The laser characteristics were: 1030 nm wavelength; pulse duration, 400 fs; and numerical aperture, 0.13. Specific software was created to custom and monitor any type of photoablation pattern for treatment purposes. Porcine crystalline lenses were placed in an open sky holder filled with physiological liquid (BSS) covered by a glass plate. A numerical camera was associated with metrological software in order to magnify and quantify the results. Transmission electron microscopy (TEM) was performed on some samples to identify the microscopic plasma interactions with the lens. The optimization of parameters was investigated in terms of the optical breakdown threshold, the sizing of interactions, and the best pattern for alignments. More than 150 crystalline lenses of freshly enucleated pigs were treated. RESULTS: The optical breakdown threshold (OBT) was defined as the minimal energy level per pulse necessary to observe a physical interaction. In our study, the OBT varied according to the following parameters: the crystalline lens itself, varying from 4.2 to 7.6 µJ (mean, 5.1 µJ), and the depth of laser focus, varying up to 1 µJ, increasing in the depth of the tissue. Analyzing the distance between impacts, we observed that the closer the impacts were the less power was needed to create a clear well-drawn defect pattern (lines), i.e., with a 4-µJ optimized OBT, when the impacts were placed every 2 µm for the x,y directions and 60 µm for the z direction. Coalescent bubbles created by plasma formation always disappeared in less than 24h. The nonthermal effect of plasma and the innocuousness on surrounding tissues were proven by the TEM results. DISCUSSION: The crystalline lens photodisruption by the femtosecond laser seems an innovative technique usable in the ultra precise crystalline lens cutting. Experimental studies in vivo are necessary in order to define of them the applications (surgery of the cataract and presbyopia) and limits in the cavitations bubbles kinetic and transfer.

[Cat-scratch disease neuroretinitis]. / Neurorétinite à Bartonella henselae: maladie des griffes du chat.

We report a case of cat-scratch disease neuroretinitis for which systemic and ocular investigations proved the responsibility of Bartonella henselae. An 11-year-old boy was referred to the hospital in November 2002 for severe visual loss in the left eye over the preceding 2 weeks. At the same time, he also developed a flu-like illness. The best corrected acuity in the left eye was counting fingers at 30 cm. Posterior segment examination on the left eye showed an optic disk edema with papillary and peripapillary hemorrhages and serous retinal detachment, mild vitreous inflammation, and two little perivascular white spots. The medical history was unremarkable except for a cat scratch on his left forearm 2 months before. Four weeks of antibiotic therapy including oral rifampin and doxycycline was used. Bartonella henselae immunoglobulin M were first detected with Bartonella henselae immunoglobulin G testing negative at this time. A 3-week serum showed immunoglobulin M seroreversion, while Bartonella henselae immunoglobulin G appeared. Other causes of optic disk edema with macular star were excluded by biological data. Bartonella antibodies to both Bartonella henselae and Bartonella clarridgeiae were detected in the cat. Ophthalmic follow-up showed progressive resorption of the neuroretinitis and the visual acuity increased to 5/10. The significance of this case report lies in the reminder that this pathology can be the cause of neuroretinitis; the prognosis can be improved by earlier treatment.